Construction method of mass concrete wall structure

Abstract

The invention relates to the technical field of civil construction, and particularly discloses a construction method of a mass concrete wall body structure, which comprises the following steps of: performing block design on the mass concrete wall body structure, longitudinally dividing the mass concrete wall body structure into a plurality of layers and transversely dividing the mass concrete wall body structure into a plurality of sections, and sequentially constructing a plurality of inclined steps along a certain direction, block pouring is carried out according to the construction sequence, the temperature difference in the mass concrete poured at a time can be reduced, the crack risk caused by temperature stress and shrinkage is reduced, generation of a large number of long and deep cracks is avoided, and the better construction quality of the mass concrete structure is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of civil construction, and in particular to a construction method for a large-volume concrete wall structure. Background Art

[0002] Concrete walls are a very common structural form in the construction process. It has the advantages of good bearing capacity, high durability, and simple construction, so it is widely used in residential, commercial buildings, infrastructure and other fields. The construction process of concrete walls is a complex process that requires precise control. The conventional steps include preparation, foundation treatment, reinforcement engineering, concrete pouring, maintenance and demoulding.

[0003] With the rapid development of the construction industry, super-large buildings and large-span structures are increasing, and large-volume concrete wall structures have gradually been widely used. Massive concrete refers to concrete that is poured in a large enough volume to produce significant temperature gradients and stresses inside the concrete. Due to the heat release of the hydration reaction, the temperature inside the concrete will rise significantly, and the temperature difference between the surface and the inside may cause concrete cracks. For example, a large-volume concrete structure with a minimum geometric dimension of not less than 1m is a typical mass concrete.

[0004] A certain area has high temperature, low humidity and little rain all year round, and the on-site construction conditions are poor. Due to the rapid evaporation of water or thermal expansion, large-volume concrete wall structures are constructed using conventional one-time pouring construction methods, which will cause a large number of deep and long cracks in the concrete walls, seriously affecting the construction quality.

[0005] Therefore, it is of great significance to develop a construction method for large-volume concrete wall structures suitable for special high-temperature environments to avoid the occurrence of a large number of deep and long cracks. Summary of the invention

[0006] The purpose of the present invention is to provide a construction method for a large-volume concrete wall structure in view of the technical problem that in the prior art, a large-volume concrete wall is constructed under special natural conditions of high temperature, and the constructed concrete structure is prone to a large number of deep and long cracks.

[0007] The present invention divides the large-volume concrete wall structure into blocks, divides it into several layers vertically and several sections horizontally, and then sequentially constructs multiple oblique steps along a certain direction. By casting in blocks in this construction sequence, the temperature difference inside the large-volume concrete cast at one time can be reduced, the risk of cracks caused by temperature stress and shrinkage can be reduced, and the occurrence of a large number of longer and deeper cracks can be avoided, thereby achieving better construction quality of the large-volume concrete structure.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A construction method for a large-volume concrete wall structure comprises the following steps:

[0010] S1. Design the wall in blocks: divide it into several layers in the vertical direction, namely the 1st layer, the 2nd layer, ... the nth layer from bottom to top, and divide it into several sections in the horizontal direction, namely the 1st section, the 2nd section, ... the mth section from one end to the other; n and m are both integers ≥ 2;

[0011] S2. Wall casting in blocks:

[0012] S21, pouring the first layer and first section of the positioned wall block, completing the construction of the first oblique step;

[0013] S22, pouring the wall blocks positioned in the second section of the first layer, pouring the wall blocks positioned in the first section of the second layer, and completing the construction of the second oblique step;

[0014] S23, pouring the wall blocks positioned at the third section of the first layer, pouring the wall blocks positioned at the second section of the second layer, pouring the wall blocks positioned at the first section of the third layer, and completing the construction of the third oblique step;

[0015] Complete the pouring of all the wall blocks of the entire wall in sequence according to the same construction sequence rules of the S21-S23 oblique steps;

[0016] Before pouring the wall blocks, the adjacent wall blocks need to be demoulded;

[0017] Among them, when the construction of the inclined steps reaches the designed height or length of the wall, it will stop and continue with the construction of the next layer or the next section.

[0018] The present invention provides a construction method for a large-volume concrete wall structure. The large-volume concrete wall structure is designed in blocks, divided into several layers vertically and several sections horizontally, and then a plurality of inclined steps are sequentially constructed along a certain direction. By casting in blocks in this construction sequence, the temperature difference inside the large-volume concrete cast at one time can be reduced, the risk of cracks caused by temperature stress and shrinkage can be reduced, the generation of a large number of longer and deeper cracks can be avoided, and better construction quality of the large-volume concrete structure can be achieved.

[0019] Furthermore, S2, during the wall block casting process, it also includes cleaning up debris from adjacent boundary positions of the wall blocks to be cast.

[0020] Furthermore, before S2, it also includes measuring and laying out at the designed location for wall construction.

[0021] Furthermore, the interval between pouring concrete of two adjacent wall blocks shall not exceed 7 days.

[0022] Furthermore, S2, during the process of pouring the wall blocks, the adjacent surfaces of the poured adjacent wall blocks are roughened.

[0023] Furthermore, the method for casting the wall block comprises the following steps:

[0024] Tie the steel cage at the designed position of the wall block;

[0025] Install concrete pouring forms and clean the pouring space from water, dust and / or debris;

[0026] Pour concrete into the formwork and let it stand;

[0027] Among them, the temperature of concrete entering the mold is controlled within 32°C, and the time from concrete mixing to final pouring is controlled within 90 minutes.

[0028] Furthermore, when pouring concrete, vibration operation needs to be performed on the top of the formwork.

[0029] Furthermore, the time of each vibration is controlled within 15-20 seconds, and the distance between adjacent vibration points is within 20-50 cm; the vibrating rod should be inserted into the lower layer of concrete by 10-15 cm.

[0030] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0031] 1. The present invention provides a construction method for a large-volume concrete wall structure, in which the large-volume concrete wall structure is designed in blocks, divided into several layers vertically and several sections horizontally, and then a plurality of inclined steps are sequentially constructed along a certain direction. By casting in blocks in this construction sequence, the temperature difference inside the large-volume concrete cast at one time can be reduced, the risk of cracks caused by temperature stress and shrinkage can be reduced, and the occurrence of a large number of longer and deeper cracks can be avoided, thereby achieving the construction quality of the large-volume concrete structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is an aerial photo of the water intake pump station in Example 1.

[0033] Figure 2 A schematic diagram of the wall block division and construction sequence of the large-volume concrete wall structure provided by the present invention.

[0034] Figure 3 This is a picture showing the process of repairing a small number of cracks on the exterior of the wall after construction.

[0035] Icon: 1-Wall block. DETAILED DESCRIPTION

[0036] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0037] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0038] Unless otherwise specified, in the description of the specific embodiments of the present invention, the terms indicating the orientation or position relationship such as "up", "down", "left", "right", "center", "inside", "outside", etc. are all expressions based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invented product / equipment / device is placed when it is usually used. These terms of orientation or position relationship are only for the convenience of describing the scheme of the present invention or simplifying the description in the specific embodiments, so as to facilitate the technicians to quickly understand the scheme, and do not indicate or imply that a specific device / component / element must have a specific orientation, or be constructed and operated in a specific position relationship, and therefore cannot be understood as a limitation on the present invention.

[0039] In addition, if the terms "horizontal", "vertical", "overhanging", "parallel" and the like appear, it does not mean that the corresponding devices / components / elements are required to be absolutely horizontal or vertical or overhanging or parallel, but may be slightly tilted or have deviations. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but may be slightly tilted. Alternatively, it can be simplified to mean that the corresponding devices / components / elements are set in directions such as "horizontal", "vertical", "overhanging", "parallel", etc., and can have an error / deviation of ±10% relative to the corresponding direction setting, more preferably an error / deviation within ±8%, more preferably an error / deviation within ±6%, more preferably an error / deviation within ±5%, and more preferably an error / deviation within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its role in the scheme of the present invention.

[0040] In addition, the expressions “first”, “second”, “third”, etc. that appear in the terms are merely descriptions used to distinguish the same or similar components and should not be understood as emphasizing or implying the relative importance of specific components.

[0041] In addition, in the description of the embodiments of the present invention, "several", "plurality" and "a number" represent at least 2. It can be any number such as 2, 3, 4, 5, 6, 7, 8, 9, and even more than 9.

[0042] In addition, in the description of the technical solution of the present invention, unless otherwise clearly specified / defined / restricted, the terms "set", "install", "connect", "connected", "provided with", "laid", and "arranged" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, and can be welding, riveting, bolting, threading, and other commonly used connection means in the field. This connection can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the internal connection of two elements.

[0043] Example 1

[0044] like Figure 1 As shown in the figure, the pump station of the JCPDI seawater cooling project (Phase I) is an onshore reinforced concrete structure, which is arranged in an east-west direction and the structural axis is perpendicular to the coastline. The water intake pump station consists of a sedimentation tank, a filtration station, a transition section, a pump station flow channel and a pump cabin. The total length of the pump station is 108.6m, the height is 23m, the sedimentation tank and the filtration station are 28m wide, the total width of the pump station flow channel area is 38.7m, and the concrete volume is about 26,000 cubic meters (excluding the upper electrical room, control room and motor hall). The concrete walls of the water intake pump station can be divided into two categories according to their location: outer walls and inner walls. The thickness of the outer walls in areas above -1.5m above sea level is 1m. Below -1.5m above sea level, the thickness of the outer walls on the north and south sides of the sedimentation tank and the filtration station is 2.5m. The thickness of the outer walls on the west and east sides of the pump station and the transition section, as well as the outer walls on the north and south sides of the pump station flow channel is 1.5m. The thickness of the diversion wall of the internal flow channel of the pump station is 0.9m, and the thickness of the sedimentation tank partition wall, the filtration station diversion wall and the sand retaining wall in the flow channel area of ​​the pump station is 1m.

[0045] The on-site construction conditions are as follows:

[0046] Temperature: The average monthly temperature is 28-36℃, and the highest temperature in summer can reach 50℃.

[0047] Rainfall: The average annual rainfall is about 155 mm, with more rainfall in January, August, and October-December. Based on field experience, there is a possibility of sudden storms. On July 29, 2016 alone, the rainfall reached 104.4 mm.

[0048] Wind speed: Mainly west and southwest winds, with an average wind speed of 4-6m / s and gusts of 9-12m / s. Sudden and strong winds may occur in summer. According to on-site experience, the maximum wind speed reached 42m / s (level 13) on the evening of July 29, 2016.

[0049] For large-volume concrete structures such as water pump concrete walls, it should be noted that cracks are very likely to appear in the concrete walls during the construction phase, affecting the quality and safety of the concrete walls.

[0050] The main reasons for cracks in large concrete structures during the construction phase include:

[0051] (1) Adiabatic temperature rise caused by hydration heat: It is related to the amount of cement and the type of cement in the unit volume of concrete, and increases exponentially with the age of concrete, generally reaching the final adiabatic temperature rise in about 10 days. However, due to the natural heat dissipation of the structure, the actual maximum temperature inside the concrete mostly occurs 3 to 5 days after the concrete is poured.

[0052] (2) Internal temperature of concrete = pouring temperature + hydration heat adiabatic temperature rise - structural heat dissipation cooling The higher the outside temperature, the higher the pouring temperature of concrete; if the outside temperature drops, the cooling range of concrete will increase. Especially when the temperature drops suddenly, the temperature gradient inside and outside the concrete will increase, which is extremely unfavorable for large-volume concrete.

[0053] (3) Concrete shrinkage is mainly caused by the evaporation of excess water in the concrete, which causes the concrete volume to shrink during drying. (If this shrinkage is constrained, shrinkage stress will be generated.) Concrete drying shrinkage is reversible to a large extent.

[0054] (4) In addition to drying shrinkage, concrete also has carbonation deformation. That is, CO2 in the air reacts with Ca(OH)2 in the concrete cement to form calcium carbonate CaCO3, which releases bound water and causes concrete to shrink.

[0055] This project is located in the JZ area with high temperature, low humidity and little rain all year round. The site conditions are harsh and the control of concrete under the on-site construction conditions is relatively difficult. The main difficulties are as follows:

[0056] Rapid evaporation of moisture: High temperature will accelerate the evaporation of moisture in concrete, causing early shrinkage of concrete and prone to cracks.

[0057] Thermal expansion: High temperatures will cause the internal temperature of the concrete to rise, causing volume expansion, which will produce thermal stress after cooling and lead to cracks.

[0058] Changes in material properties:

[0059] Changes in material properties will result in data monitoring of concrete durability, concrete strength development and on-site temperature control.

[0060] In order to adapt to the construction of concrete structures in this special environment, temperature control measures are required for large-volume concrete, including:

[0061] Temperature before entering the mold: Controlling the temperature of concrete before entering the mold can effectively slow down the early hydration heat release and prevent cracks caused by rapid temperature changes. Temperature detection should be carried out before and after mixing and pouring. The temperature after mixing should be controlled within 25°C and the temperature before entering the mold should be controlled within 32°C.

[0062] Maximum temperature: The maximum temperature inside the concrete has a direct impact on its long-term performance and durability. Excessive temperature will aggravate thermal stress and cause cracks. Use temperature sensors for real-time monitoring to ensure that the maximum temperature does not exceed 70°C.

[0063] Maximum temperature rise: Excessive temperature rise will increase the internal temperature difference, causing thermal stress and cracking. Check the temperature regularly during pouring and curing to ensure that the temperature rise is controlled within the range of 20-25℃.

[0064] Temperature difference between inside and outside: Controlling the temperature difference between inside and outside can reduce the occurrence of surface cracks and ensure the safety of the structure. Use temperature sensors for real-time monitoring to ensure that the temperature difference between inside and outside does not exceed 20°C.

[0065] Since the wall area of ​​the water pump is large, under such special natural conditions, if the pouring is completed in one go, or if the concrete wall structure is poured in blocks in a random manner, the temperature difference will be large, and a large number of cracks will easily appear.

[0066] To this end, the present invention provides a construction method for a large-volume concrete wall. By pouring the large-volume concrete in blocks according to the design plan, the temperature difference inside the large-volume concrete poured at one time can be reduced, the risk of cracks caused by temperature stress can be reduced, cracks caused by shrinkage can be effectively controlled, and the construction quality can be improved.

[0067] The specific construction process is as follows:

[0068] A wall construction method comprises the following steps:

[0069] S1. The wall is divided into six layers in the vertical direction, namely the 1st layer, the 2nd layer, ... the 6th layer from the bottom to the top, and four sections in the horizontal direction, namely the 1st section, the 2nd section, ... the 4th section from one end to the other; each section of each layer is a wall block;

[0070] Specific as Figure 2 As shown, the pouring of wall blocks adopts ①- Pour in the order of.

[0071] S2. Wall casting in blocks:

[0072] S21, pouring the first layer and the first section of the positioned wall block 1, completing the construction of the first oblique step;

[0073] S22, pouring the wall block 1 of the first layer and the second section, pouring the wall block 1 of the second layer and the first section, completing the construction of the second oblique step;

[0074] S23, pouring the wall block 1 of the third section of the first layer, pouring the wall block 1 of the second section of the second layer, pouring the wall block 1 of the first section of the third layer, and completing the construction of the third oblique step;

[0075] S24, pouring the wall block 1 of the 4th section of the 1st layer, pouring the wall block 1 of the 3rd section of the 2nd layer, pouring the wall block 1 of the 2nd section of the 3rd layer, pouring the wall block 1 of the 1st section of the 4th layer, and completing the construction of the fourth oblique step;

[0076] S25, pouring the wall block 1 of the 4th section of the 2nd floor, pouring the wall block 1 of the 3rd section of the 3rd floor, pouring the wall block 1 of the 2nd section of the 4th floor, pouring the wall block 1 of the 1st section of the 5th floor, and completing the construction of the fifth oblique step;

[0077] S26, pouring the wall block 1 of the 4th section of the 3rd floor, pouring the wall block 1 of the 3rd section of the 4th floor, pouring the wall block 1 of the 2nd section of the 5th floor, pouring the wall block 1 of the 1st section of the 6th floor, and completing the construction of the sixth oblique step;

[0078] S27, pouring the wall block 1 positioned at the 4th section of the 4th floor, pouring the wall block 1 positioned at the 3rd section of the 5th floor, pouring the wall block 1 positioned at the 2nd section of the 6th floor to complete the construction of the seventh oblique step.

[0079] S28, pouring the wall block 1 positioned at the 4th section of the 5th floor, and pouring the wall block 1 positioned at the 3rd section of the 6th floor to complete the construction of the eighth oblique step.

[0080] S29, pouring the wall block 1 positioned in the 4th section of the 6th floor, completing the construction of the ninth inclined step.

[0081] Before pouring the wall block 1, the wall block 1 at the adjacent position needs to be demolded;

[0082] Among them, when the construction of the inclined step reaches the designed height or length of the wall, it stops and the construction of the next inclined step is postponed.

[0083] It has been verified that the block pouring through the above-mentioned construction sequence can reduce the temperature difference inside the large volume concrete poured at one time, reduce the risk of cracks caused by temperature stress and shrinkage, avoid the occurrence of a large number of longer and deeper cracks, and achieve the construction quality of large-volume concrete structures.

[0084] In some embodiments, S2, during the wall block casting process, the process also includes cleaning debris from adjacent boundary positions of the wall block 1 to be cast.

[0085] In some implementations, before S2, it also includes measuring and setting out the wall at the designed construction location.

[0086] In some embodiments, the interval between the concrete pouring of two adjacent wall blocks 1 is no more than 7 days. If the concrete pouring interval is controlled within a reasonable time, the connection between the two wall blocks 1 will be better and no cracks will appear.

[0087] Furthermore, S2, during the process of pouring the wall blocks, the adjacent surfaces of the poured adjacent wall blocks 1 are roughened.

[0088] Furthermore, the method for casting the wall block 1 comprises the following steps:

[0089] Tie the steel cage at the designed position of wall block 1;

[0090] Install concrete pouring forms and clean the pouring space from water, dust and / or debris;

[0091] Pour concrete into the formwork and let it stand;

[0092] Among them, the temperature of concrete entering the mold is controlled within 32°C, and the time from concrete mixing to final pouring is controlled within 90 minutes.

[0093] Reasonable control of the concrete mold temperature and pouring time can avoid a large number of cracks on the wall block 1 and ensure the internal quality and external appearance of the wall block 1.

[0094] In some embodiments, when pouring concrete, it is necessary to perform a vibration operation on the top of the formwork.

[0095] In some embodiments, the duration of each vibration is controlled within 15-20 seconds, and the distance between adjacent vibration points is within 20-50 cm; the vibrating rod should be inserted into the lower layer of concrete by 10-15 cm.

[0096] During the concrete construction process, the construction workers stand on the operating platform on the top of the formwork to perform the vibration operation. The vibration uses a 50-type inserted vibrator. The time of each vibration is controlled within 15-20 seconds, and the distance between the vibration points is between 40-50cm. When vibrating, the vibrator should be inserted into the lower layer of concrete by 10-15cm to ensure the effective combination of the upper and lower layers of concrete. At the same time, care should be taken to avoid steel bars, embedded parts, round cone nuts and embedded anchor rods. The minimum distance between the vibrator and the side formwork is controlled at 5-10cm, and the side formwork must not be touched. The vibrator should be inserted quickly and pulled out slowly, and vibrated until the concrete surface is flat, without slurry or bubbles. No missing vibration or over-vibration is allowed. It is strictly forbidden to add water to the concrete during the pouring process. If the concrete workability is found to be poor, the concrete tanker should rotate 5 times at a uniform speed, and then take other measures to strengthen the vibration and improve the workability.

[0097] During the concrete pouring period, arrange personnel to regularly inspect the formwork, paying special attention to the bolt connection and whether there is leakage in the formwork. If the above problems occur, notify the formwork workers in time to tighten or seal them.

[0098] like Figure 3 As shown, after investigation, the width of the cracks is less than 0.05mm and the crack depth is shallow. These are cracks formed due to water loss and shrinkage of hardened concrete during the drying process. The overall quality of the repairs is controllable according to the concrete repair plan reported to the owner.

[0099] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A construction method for a large-volume concrete wall structure, characterized in that: The following steps are involved: S1. Design the wall in blocks: divide it into several layers in the vertical direction, namely the 1st layer, the 2nd layer, ... the nth layer from bottom to top, and divide it into several sections in the horizontal direction, namely the 1st section, the 2nd section, ... the mth section from one end to the other; n and m are both integers ≥ 2; S2. Wall casting in blocks: S21, pouring the first layer and first section of the positioned wall block, completing the construction of the first oblique step; S22, pouring the wall blocks positioned in the second section of the first layer, pouring the wall blocks positioned in the first section of the second layer, and completing the construction of the second oblique step; S23, pouring the wall blocks positioned at the third section of the first layer, pouring the wall blocks positioned at the second section of the second layer, pouring the wall blocks positioned at the first section of the third layer, and completing the construction of the third oblique step; Complete the pouring of all the wall blocks of the entire wall in sequence according to the same construction sequence rules of the S21-S23 inclined steps; Before pouring the wall blocks, the adjacent wall blocks need to be demoulded; Among them, when the construction of the inclined steps reaches the designed height of the nth layer of the wall or the designed length of the mth section of the wall, it stops and the construction of the next layer or the next section is continued.

2. The construction method of a large-volume concrete wall structure according to claim 1, characterized in that: S2, during the process of pouring the wall blocks, it also includes cleaning the adjacent boundary positions of the wall blocks to be poured.

3. The construction method of a large-volume concrete wall structure according to claim 1, characterized in that: Before S2, it also includes measurement and layout at the designed location of wall construction.

4. The construction method of a large-volume concrete wall structure according to claim 1, characterized in that: The interval between pouring concrete of two adjacent wall blocks shall not exceed 7 days.

5. The construction method of a large-volume concrete wall structure according to claim 1, characterized in that: S2, during the process of pouring the wall in blocks, the adjacent surfaces of the poured adjacent wall blocks are roughened.

6. The construction method of a large-volume concrete wall structure according to any one of claims 1 to 5, characterized in that: The method for pouring the wall blocks comprises the following steps: Tie the steel cage at the designed position of the wall block; Install concrete pouring forms and clean the pouring space from water, dust and / or debris; Pour concrete into the formwork and let it stand; Among them, the temperature of concrete entering the mold is controlled within 32°C, and the time from concrete mixing to final pouring is controlled within 90 minutes.

7. The construction method of a large-volume concrete wall structure according to claim 6, characterized in that: When pouring concrete, vibration work needs to be carried out on the top of the formwork.

8. The construction method of a large-volume concrete wall structure according to claim 7, characterized in that: The time of each vibration should be controlled within 15-20 seconds, and the distance between adjacent vibration points should be within 20-50cm; the vibrating rod should be inserted 10-15cm into the lower layer of concrete.

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